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JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ReadPreference = exports.ReadPreferenceMode = void 0;
const error_1 = require("./error");
/** @public */
exports.ReadPreferenceMode = Object.freeze({
primary: 'primary',
primaryPreferred: 'primaryPreferred',
secondary: 'secondary',
secondaryPreferred: 'secondaryPreferred',
nearest: 'nearest'
});
/**
* The **ReadPreference** class is a class that represents a MongoDB ReadPreference and is
* used to construct connections.
* @public
*
* @see https://www.mongodb.com/docs/manual/core/read-preference/
*/
class ReadPreference {
/**
* @param mode - A string describing the read preference mode (primary|primaryPreferred|secondary|secondaryPreferred|nearest)
* @param tags - A tag set used to target reads to members with the specified tag(s). tagSet is not available if using read preference mode primary.
* @param options - Additional read preference options
*/
constructor(mode, tags, options) {
if (!ReadPreference.isValid(mode)) {
throw new error_1.MongoInvalidArgumentError(`Invalid read preference mode ${JSON.stringify(mode)}`);
}
if (options == null && typeof tags === 'object' && !Array.isArray(tags)) {
options = tags;
tags = undefined;
}
else if (tags && !Array.isArray(tags)) {
throw new error_1.MongoInvalidArgumentError('ReadPreference tags must be an array');
}
this.mode = mode;
this.tags = tags;
this.hedge = options?.hedge;
this.maxStalenessSeconds = undefined;
this.minWireVersion = undefined;
options = options ?? {};
if (options.maxStalenessSeconds != null) {
if (options.maxStalenessSeconds <= 0) {
throw new error_1.MongoInvalidArgumentError('maxStalenessSeconds must be a positive integer');
}
this.maxStalenessSeconds = options.maxStalenessSeconds;
// NOTE: The minimum required wire version is 5 for this read preference. If the existing
// topology has a lower value then a MongoError will be thrown during server selection.
this.minWireVersion = 5;
}
if (this.mode === ReadPreference.PRIMARY) {
if (this.tags && Array.isArray(this.tags) && this.tags.length > 0) {
throw new error_1.MongoInvalidArgumentError('Primary read preference cannot be combined with tags');
}
if (this.maxStalenessSeconds) {
throw new error_1.MongoInvalidArgumentError('Primary read preference cannot be combined with maxStalenessSeconds');
}
if (this.hedge) {
throw new error_1.MongoInvalidArgumentError('Primary read preference cannot be combined with hedge');
}
}
}
// Support the deprecated `preference` property introduced in the porcelain layer
get preference() {
return this.mode;
}
static fromString(mode) {
return new ReadPreference(mode);
}
/**
* Construct a ReadPreference given an options object.
*
* @param options - The options object from which to extract the read preference.
*/
static fromOptions(options) {
if (!options)
return;
const readPreference = options.readPreference ?? options.session?.transaction.options.readPreference;
const readPreferenceTags = options.readPreferenceTags;
if (readPreference == null) {
return;
}
if (typeof readPreference === 'string') {
return new ReadPreference(readPreference, readPreferenceTags, {
maxStalenessSeconds: options.maxStalenessSeconds,
hedge: options.hedge
});
}
else if (!(readPreference instanceof ReadPreference) && typeof readPreference === 'object') {
const mode = readPreference.mode || readPreference.preference;
if (mode && typeof mode === 'string') {
return new ReadPreference(mode, readPreference.tags ?? readPreferenceTags, {
maxStalenessSeconds: readPreference.maxStalenessSeconds,
hedge: options.hedge
});
}
}
if (readPreferenceTags) {
readPreference.tags = readPreferenceTags;
}
return readPreference;
}
/**
* Replaces options.readPreference with a ReadPreference instance
*/
static translate(options) {
if (options.readPreference == null)
return options;
const r = options.readPreference;
if (typeof r === 'string') {
options.readPreference = new ReadPreference(r);
}
else if (r && !(r instanceof ReadPreference) && typeof r === 'object') {
const mode = r.mode || r.preference;
if (mode && typeof mode === 'string') {
options.readPreference = new ReadPreference(mode, r.tags, {
maxStalenessSeconds: r.maxStalenessSeconds
});
}
}
else if (!(r instanceof ReadPreference)) {
throw new error_1.MongoInvalidArgumentError(`Invalid read preference: ${r}`);
}
return options;
}
/**
* Validate if a mode is legal
*
* @param mode - The string representing the read preference mode.
*/
static isValid(mode) {
const VALID_MODES = new Set([
ReadPreference.PRIMARY,
ReadPreference.PRIMARY_PREFERRED,
ReadPreference.SECONDARY,
ReadPreference.SECONDARY_PREFERRED,
ReadPreference.NEAREST,
null
]);
return VALID_MODES.has(mode);
}
/**
* Validate if a mode is legal
*
* @param mode - The string representing the read preference mode.
*/
isValid(mode) {
return ReadPreference.isValid(typeof mode === 'string' ? mode : this.mode);
}
/**
* Indicates that this readPreference needs the "SecondaryOk" bit when sent over the wire
* @see https://www.mongodb.com/docs/manual/reference/mongodb-wire-protocol/#op-query
*/
secondaryOk() {
const NEEDS_SECONDARYOK = new Set([
ReadPreference.PRIMARY_PREFERRED,
ReadPreference.SECONDARY,
ReadPreference.SECONDARY_PREFERRED,
ReadPreference.NEAREST
]);
return NEEDS_SECONDARYOK.has(this.mode);
}
/**
* Check if the two ReadPreferences are equivalent
*
* @param readPreference - The read preference with which to check equality
*/
equals(readPreference) {
return readPreference.mode === this.mode;
}
/** Return JSON representation */
toJSON() {
const readPreference = { mode: this.mode };
if (Array.isArray(this.tags))
readPreference.tags = this.tags;
if (this.maxStalenessSeconds)
readPreference.maxStalenessSeconds = this.maxStalenessSeconds;
if (this.hedge)
readPreference.hedge = this.hedge;
return readPreference;
}
}
ReadPreference.PRIMARY = exports.ReadPreferenceMode.primary;
ReadPreference.PRIMARY_PREFERRED = exports.ReadPreferenceMode.primaryPreferred;
ReadPreference.SECONDARY = exports.ReadPreferenceMode.secondary;
ReadPreference.SECONDARY_PREFERRED = exports.ReadPreferenceMode.secondaryPreferred;
ReadPreference.NEAREST = exports.ReadPreferenceMode.nearest;
ReadPreference.primary = new ReadPreference(exports.ReadPreferenceMode.primary);
ReadPreference.primaryPreferred = new ReadPreference(exports.ReadPreferenceMode.primaryPreferred);
ReadPreference.secondary = new ReadPreference(exports.ReadPreferenceMode.secondary);
ReadPreference.secondaryPreferred = new ReadPreference(exports.ReadPreferenceMode.secondaryPreferred);
ReadPreference.nearest = new ReadPreference(exports.ReadPreferenceMode.nearest);
exports.ReadPreference = ReadPreference;
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